This project attempts to identify the gene(s) that predispose individuals to the hereditary form of juvenile psoriasis using a reverse genetic approach. Blood samples are collected from affected and unaffected members of large psoriatic kindreds or from families with at least two affected siblings and DNA made from the blood is analyzed for polymorphic markers spanning the entire genome. Statistical linkage analysis is used to detect linkage of psoriasis to a particular marker. Further studies will attempt to establish the gene(s) involved and the specific defect(s).